Metadata: Identification_Information: Citation: Citation_Information: Originator: U.S. Geological Survey Originator: Coastal and Marine Geology Program Publication_Date: 2013 Title: l1081na.m77t - MGD77 data file for Geophysical data from field activity L-10-81-AA in North Aleutians, Alaska from 08/16/1981 to 08/23/1981 Geospatial_Data_Presentation_Form: tab-delimited ASCII text files Publication_Information: Publication_Place: Menlo Park, CA Publisher: U.S. Geological Survey Online_Linkage: http://www.ngdc.noaa.gov/mgg/trk/trackline/samuel_p._lee/l1081na/mgd77/ Larger_Work_Citation: Citation_Information: Originator: Wm. Clinton Steele Originator: Carolyn H. Degnan Originator: Gary B. Deeter Originator: Jean A. Riordan Publication_Date: 1980 Title: DESCRIPTION OF MARINE GEOPHYSICAL DATA COLLECTED BY THE U.S. GEOLOGICAL SURVEY AND HOW TO OBTAIN IT Edition: 1.0 Geospatial_Data_Presentation_Form: Digital Document Series_Information: Series_Name: U.S. Geological Survey Open File Report Issue_Identification: 167 Publication_Information: Publication_Place: Menlo Park, CA Publisher: U.S. Geological Survey Online_Linkage: http://pubs.usgs.gov/of/1989/0167/report.pdf Description: Abstract: Single-beam bathymetry data along with DGPS navigation data was collected as part of field activity L-10-81-AA in North Aleutians, Alaska from 08/16/1981 to 08/23/1981, The geophysical source was a Knudsen 12 kHz 320B/R echosounder. These data are reformatted from space-delimited ASCII text files located in the Coastal and Marine Geology Program (CMGP) InfoBank field activity catalog at http://walrus.wr.usgs.gov/infobank/l/l1081aa/html/l-10-81-aa.bath.html into MGD77T format provided by the NOAA's National Geophysical Data Center(NGDC). The MGD77T format includes a header (documentation) file (.h77t) and a data file (.m77t). More information regarding this format can be found in the publication listed in the Cross_reference section of this metadata file. Purpose: These data and information are intended for science researchers,students, policy makers, and general public. These data are not to be used for navigation purposes. The data are reformatted into MGD77T standard format for inclusion into NOAA's NGDC geophysical database. From there the data will be made available to GeoMapApp ( http://www.geomapapp.org/ ) and Virtual Ocean ( http://www.virtualocean.org/ ) Earth-browsing software. Access to the data is also provided via the USGS Coastal and Marine Geoscience Data System ( http://cmgds.marine.usgs.gov/ ). Supplemental_Information: The navigation data are digitally collected using a Satellite Integrated Navigation (SINS) system. The system is a space-based satellite navigation maintained by the United States government and is accessible using a satellite receiver. This system provides navigational accuracy of approximately 200 m.The Data Acquistion, Processing, and Storage (DAPS) group performs a number of processing steps to the navigation data once it is collected which can vary by cruise. These steps are outlined within the header information in each individual digital navigation (.05x) space-delimited ASCII data file. The header information rows are indicated by lines beginning with the character "!". There is no information on how the single-beam bathymetry, gravity, and magnetic data were collected. For each data gathering cruise leg, the available data in the following categories are forwarded to NGDC: navigation, gravity, magnetics, bathymetry, and seismic shot points. The available data for each cruise leg are re-formatted and combined into the Marine Geophysical Data Exchange Format (MGD77) and into the internal NGDC SEIS-NAV format by USGS using several USGS developed FORTRAN programs.The FORTRAN programs sample the navigation to every integer minute of the cruise. When necessary, the latitudes and longitudes are linearly interpolated. If the time between the actual navigation fixes exceeds five minutes, no data are included in the MGD77 file.To build the MGD77 file, gravity, magnetics, and bathymetry are added to this sampled navigation. When necessary, gravity, magnetics, and bathymetry data are linearly interpolated if the time between the actual data samples does not exceed five minutes. If a time gap exceeds this, the data are not reported.The navigation data are merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data are interpolated for each shot point. Both types of files are written to magnetic tape and sent to NGDC. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 19810816 Ending_Date: 19810823 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -166.52417 East_Bounding_Coordinate: -160.73595 North_Bounding_Coordinate: 56.89931 South_Bounding_Coordinate: 53.89505 Keywords: Theme: Theme_Keyword_Thesaurus: USGS Metadata Identifier Theme_Keyword: USGS:94226987-4021-44a2-9ef2-89e5d33bdbc4 Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificinformation Theme_Keyword: oceans Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: Marine Geology Theme_Keyword: Marine Geophysics Theme_Keyword: Bathymetry Theme_Keyword: Water Depth Theme_Keyword: Seafloor Topography Theme: Theme_Keyword_Thesaurus: Data Categories for Marine Planning Theme_Keyword: distributions Theme_Keyword: bathymetry and elevation Theme: Theme_Keyword_Thesaurus: Marine Realms Information Bank (MRIB) keywords Theme_Keyword: single-beam echo sounder Theme_Keyword: marine geophysics Theme: Theme_Keyword_Thesaurus: USGS Thesaurus Theme_Keyword: single-beam echo sounder Theme_Keyword: bathymetry measurement Theme_Keyword: bathymetry Theme_Keyword: marine geophysics Place: Place_Keyword_Thesaurus: Geographic Names Information System (GNIS) Place_Keyword: AK Place_Keyword: Alaska Place_Keyword: Aleutian Arc Place_Keyword: Aleutians Place_Keyword: North Aleutians, Alaska Place_Keyword: USA Access_Constraints: None. These data are held in the public domain. Use_Constraints: This information is not intended for navigational purposes. Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data. Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Gregory K. Miller Contact_Organization: U.S. Geological Survey Contact_Position: Physical Scientist Contact_Address: Address_Type: mailing and physical Address: 600 4th Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: (727) 803-8747, ext. 3020 Contact_Electronic_Mail_Address: gmiller@usgs.gov Data_Set_Credit: Bruce Molnia (Chief Scientist) Cross_Reference: Citation_Information: Originator: Hittelman, Allen M., Groman, Robert C., Haworth, Richard T., Holcombe, Troy L., McHendrie, Graig, Smith, Stuart M., and Metzger, Dan R. Publication_Date: 2010 Title: The marine geophysical data exchange format - MGD77 / MGD77T Publication_Information: Publication_Place: Boulder, CO Publisher: National Geophysical Data Center, National Oceanic and Atmospheric Administration Other_Citation_Details: 25 p. Online_Linkage: http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.pdf Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The validity or accuracy of bathymetry and navigation data is highly qualitative and depends on equipment and operating condition variables. Data quality is unknown, MGD77T files were formatted from InfoBank files identified as best available version. Logical_Consistency_Report: This data set is from one field activity with unknown instrument calibrations. Processed bathymetric depths were spot checked based on latitude and longitude against the Global Multi-Resolution Topography (GMRT) grid within GeoMapApp to ensure reasonable values. Completeness_Report: Start and end date/times of data >Navigation Data (l-10-81-aa.051 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >198108161903000 198108232110000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (l-10-81-aa.335_051) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >YYYYMMDDHHMMSST YYYYMMDDHHMMSST Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Unspecified Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Unspecified Lineage: Process_Step: Process_Description: Navigation Data >Converted to time format with year at start. > >10/21/85 KAYE DRS$DATA:[LA81NA.N]LA81NA.051; >DRB0:[DRS.REFMT]REFORMAT.EXE;4 > Process_Date: 19960119 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG) Contact_Person: Carolyn H. Degnan Contact_Position: Geophysicist Contact_Address: Address_Type: mailing and physical address Address: USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive City: Santa Cruz State_or_Province: CA Postal_Code: 95060-5792 Country: USA Contact_Voice_Telephone: (831) 460-7452 Contact_Facsimile_Telephone: (831) 427-4748 Contact_Electronic_Mail_Address: infobank@octopus.wr.usgs.gov Process_Step: Process_Description: Bathymetry Data >10/31/1998 /tiger/l/l1081aa/bath/l-10-81-aa.335_051 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >09/11/85 BECKIE DUA0:[DATA.L1081AA.B]LA81NA.335; >DRB0:[DRS.NGDC]UNREFNGDC.EXE; >This file is hand-digetized bathy (some values >being interpolated). > >Input was... >Converted to time format with year at start. > >10/21/85 KAYE DRS$DATA:[LA81NA.N]LA81NA.051; >DRB0:[DRS.REFMT]REFORMAT.EXE;4 > >time, lat, long, time(sec) to nearest nav fix, data values Process_Date: 19990317 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG) Contact_Person: Carolyn H. Degnan Contact_Position: Geophysicist Contact_Address: Address_Type: mailing and physical address Address: USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive City: Santa Cruz State_or_Province: CA Postal_Code: 95060-5792 Country: USA Contact_Voice_Telephone: (831) 460-7452 Contact_Facsimile_Telephone: (831) 427-4748 Contact_Electronic_Mail_Address: infobank@octopus.wr.usgs.gov Process_Step: Process_Description: MGD77 file creation - The available data for each cruise leg are re-formatted and combined into the Marine Geophysical Data Exchange Format (MGD77) and into the internal NGDC SEIS-NAV format by USGS using several USGS developed FORTRAN programs.The FORTRAN programs sample the navigation to every integer minute of the cruise. When necessary, the latitudes and longitudes are linearly interpolated. If the time between the actual navigation fixes exceeds five minutes, no data are included in the MGD77 file.To build the MGD77 file, gravity, magnetics, and bathymetry are added to this sampled navigation. When necessary, gravity, magnetics, and bathymetry data are linearly interpolated if the time between the actual data samples does not exceed five minutes. If a time gap exceeds this, the data are not reported.The navigation data are merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data are interpolated for each shot point. Both types of files are written to magnetic tape and sent to NGDC. Process_Date: 20120620 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG) Contact_Person: Carolyn H. Degnan Contact_Position: Geophysicist Contact_Address: Address_Type: mailing and physical address Address: USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive City: Santa Cruz State_or_Province: CA Postal_Code: 95060-5792 Country: USA Contact_Voice_Telephone: (831) 460-7452 Contact_Facsimile_Telephone: (831) 427-4748 Contact_Electronic_Mail_Address: infobank@octopus.wr.usgs.gov Process_Step: Process_Description: Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Process_Date: 20170201 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: Alan O. Allwardt Contact_Position: Contractor -- Information Specialist Contact_Address: Address_Type: mailing and physical address Address: 2885 Mission Street City: Santa Cruz State_or_Province: CA Postal_Code: 95060 Contact_Voice_Telephone: 831-460-7551 Contact_Facsimile_Telephone: 831-427-4748 Contact_Electronic_Mail_Address: aallwardt@usgs.gov Process_Step: Process_Description: Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Process_Date: 20201019 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: VeeAnn A. Cross Contact_Position: Marine Geologist Contact_Address: Address_Type: Mailing and Physical Address: 384 Woods Hole Road City: Woods Hole State_or_Province: MA Postal_Code: 02543-1598 Contact_Voice_Telephone: 508-548-8700 x2251 Contact_Facsimile_Telephone: 508-457-2310 Contact_Electronic_Mail_Address: vatnipp@usgs.gov Spatial_Data_Organization_Information: Indirect_Spatial_Reference: North Aleutians, Alaska Direct_Spatial_Reference_Method: Point Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Point Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Latitude_Resolution: 0.000001 Longitude_Resolution: 0.000001 Geographic_Coordinate_Units: Decimal degrees Geodetic_Model: Horizontal_Datum_Name: D_WGS_1984 Ellipsoid_Name: WGS_1984 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.25722210100002 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: l1081na.m77t Entity_Type_Definition: MGD77T single-beam bathymetry data file for L1081AA Entity_Type_Definition_Source: NOAA's National Geophysical Data Center, See Hittelman and others (2010) Cross_Reference section above for details about the MGD77T format and citation information. Attribute: Attribute_Label: SURVEY_ID Attribute_Definition: Survey identifier supplied by the contributing organization Attribute_Definition_Source: NGDC Attribute_Domain_Values: Unrepresentable_Domain: This identifier varies in format and is supplied by the contributing organization Attribute: Attribute_Label: TIMEZONE Attribute_Definition: Time-zone correction Attribute_Definition_Source: NGDC Attribute_Domain_Values: Unrepresentable_Domain: In our datasets, no correction was applied. All values equal 0. Attribute: Attribute_Label: DATE Attribute_Definition: YYYYMMDD Attribute_Definition_Source: NGDC Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 19810816 Range_Domain_Maximum: 19810823 Attribute_Units_of_Measure: Year, month, day Attribute: Attribute_Label: TIME Attribute_Definition: Time Attribute_Definition_Source: NGDC Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 2359 Attribute_Units_of_Measure: hours and decimal minutes Attribute: Attribute_Label: LAT Attribute_Definition: Latitude Attribute_Definition_Source: World Geodetic System 1984 Geographic Coordinate System Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 53.89505 Range_Domain_Maximum: 56.89931 Attribute_Units_of_Measure: decimal degrees Attribute: Attribute_Label: LON Attribute_Definition: Longitude Attribute_Definition_Source: World Geodetic System 1984 Geographic Coordinate System Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -166.52417 Range_Domain_Maximum: -160.73594 Attribute_Units_of_Measure: decimal degrees Attribute: Attribute_Label: POS_TYPE Attribute_Definition: Indicates how lat/lon was obtained Attribute_Definition_Source: NGDC Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1 Range_Domain_Maximum: 3 Attribute_Units_of_Measure: 1 = observed fix, 3 = interpolated fix, nil = unspecified Attribute: Attribute_Label: BAT_TTIME Attribute_Definition: Bathymetry, 2-way travel time Attribute_Definition_Source: U.S. Geological Survey Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0.038 Range_Domain_Maximum: 0.95 Attribute_Units_of_Measure: seconds Attribute: Attribute_Label: CORR_DEPTH Attribute_Definition: Bathymetry, corrected depth Attribute_Definition_Source: U.S. Geological Survey Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 28.5 Range_Domain_Maximum: 712.4 Attribute_Units_of_Measure: decimal meters Attribute: Attribute_Label: BAT_CPCO Attribute_Definition: Bathymetric Correction code - details the procedure used for determining the sound velocity correction to depth Attribute_Definition_Source: NGDC Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 59 Range_Domain_Maximum: 59 Attribute_Units_of_Measure: 01-55 Matthews' Zones with zone , 59 Matthews' Zones, no zone specified, 60 S. Kuwahara Formula, 61 Wilson Formula, 62 Del Grosso Formula, 63 Carter's Tables, 88 Other (see Add. Doc.), 97 Computed using 1500 meters/sec, 98 Unknown if Corrected, 99 Unspecified Attribute: Attribute_Label: BAT_TYPCO Attribute_Definition: Bathymetry type code - indicates how the bathymetric value was obtained Attribute_Definition_Source: NGDC Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1 Range_Domain_Maximum: 1 Attribute_Units_of_Measure: 1 - Observed, 3 - Interpolated (Header Seq. 12), 9 - Unspecified Overview_Description: Entity_and_Attribute_Overview: Bathymetry and navigation data for U.S. Geological Survey bathymetry survey L1081AA in MGD77T format. Entity_and_Attribute_Detail_Citation: Attributes are obtained from MGD77T data files created from the navigation and bathymetry best files. MGD77T is the standard, defined data format used for geophysical data in the National Geophysical Data Center. See Cross_Reference section above for citation details. Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing and physical address Address: 345 Middlefield Road MS 999 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Voice_Telephone: (650) 329-5078 Contact_Facsimile_Telephone: (650) 329-5190 Resource_Description: Downloadable Data Distribution_Liability: Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: MGD77t Format_Version_Number: 10 Format_Specification: MGD77 Format_Information_Content: tab-delimited ASCII text files. Transfer_Size: .062 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://www.ngdc.noaa.gov/mgg/trk/trackline/samuel_p._lee/l1081na/mgd77/ Access_Instructions: Data are available for download on the World Wide Web (WWW). Fees: None Metadata_Reference_Information: Metadata_Date: 20201019 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Gregory K. Miller Contact_Organization: U.S. Geological Survey Contact_Position: Physical Scientist Contact_Address: Address_Type: mailing and physical address Address: U.S. Geological Survey, 600 Fourth Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: (727) 803-8747, ext. 3020 Contact_Electronic_Mail_Address: gmiller@usgs.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998